Still picture processing method and/or apparatus

ABSTRACT

A method of processing original still picture data representing an original still image and stored in a video memory and storing processed still picture data representing a processed still image in a predetermined location of the video memory comprising the steps of setting an XY orthogonal coordinate system on the video memory, setting a reference line parallel to one of the X and Y axes of the orthogonal coordinate system and passing through a point of intersection of lines, each of which connects corresponding pixels of the original and processed still images, moving multiples the pixel data on a line of the original still image parallel to the reference line and furthest from the reference line to addresses of the video memory forming a line of the processed still image, and repeating the preceding step for pixel data on lines of the still image parallel to the reference line and second furthest from the reference line and succeeding lines, to thereby store the processed still picture data representing the processed still image in the video memory. An apparatus employing this method for processing original still picture data is also provided.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to still picture processingsystems and, more particularly, is directed to a still pictureprocessing method and/or apparatus in which a processed still picturesignal of a processed still picture similar to an original still pictureof an original still picture signal stored in a memory is re-stored inthe memory at its desired address.

2. Description of the Prior Art

An example of the prior art will be explained hereinafter with referenceto FIG. 1A to 1C.

When an enlarged or magnified still picture signal of an original stillpicture signal stored in a video memory is stored in the video memory atits desired location instead of the original still picture signal insuch a manner that a magnified still picture having a rectangular areaA₂ B₂ C₂ D₂ of an original still picture having, for example, arectangular area A₁ B₁ C₁ D₁ is moved in parallel to a desired locationon a memory plane corresponding to a picture screen as shown in FIG. 1A,if the original still picture signal and the magnified still picturesignal partly or wholly overlap with each other, the original stillpicture signal of the original still picture having the rectangular areaA₁ B₁ C₁ D₁ is temporarily transferred to a buffer memory as shown inFIG. 1B, and then this still picture signal is magnified as shown inFIG. 1C and stored in the original video memory instead of the originalstill picture signal.

The example of the above-mentioned prior art, however, needs a buffermemory whose storage capacity is the same as that of the video memory,which provides an expensive apparatus for processing a still picture.Also, the original still picture signal, stored in the video memory, istransferred to the buffer memory and is again transferred to the videomemory so that a processing time for obtaining a processed still picturesignal from the original still picture signal is increased considerably.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide animproved still picture data processing method and/or apparatus which caneliminate the above-mentioned defects encountered with the prior art.

It is another object of the present invention to provide a still picturedata processing method and/or apparatus of a simplified arrangementwhich employs a memory of a small storage capacity.

It is still another object of the present invention to provide a stillpicture data processing method and/or apparatus of a simplifiedarrangement which employs a memory of high processing speed.

According to an aspect of the present invention, there is provided amethod of processing original still picture data representing anoriginal still image and stored in a video memory and storing processedstill picture data representing a processed still image in apredetermined location of said video memory, said method comprising thesteps of:

(a) setting an XY orthogonal coordinate system on said video memory;

(b) setting a reference line parallel to one of X and Y axes of saidorthogonal coordinate system and passing through a point of intersectionof lines, each of which connects corresponding pixels of said originaland processed still images;

(c) moving the pixel data on a line of said original still imageparallel to said reference line and furthest from said reference line toaddresses of said video memory forming a line of said processed stillimage; and

(d) repeating the preceding step for pixel data on lines of said stillimage parallel to said reference line and second furthest from saidreference line and succeeding lines, to thereby store the processedstill picture data representing said processed still image in said videomemory.

According to another aspect of the present invention, there is providedan apparatus for processing an original still picture data representingan original still image and generating a processed still picture datarepresenting a processed still image comprising:

(1) video memory means for storing said original still picture data andsaid processed still picture data;

(2) means for setting an XY orthogonal coordinate system on said videomemory means;

(3) means for setting a reference line parallel to one of X and Y axesof said orthogonal coordinate system and passing through a point ofintersection of lines, each of which connects corresponding pixels ofsaid original and processed still images; and

(4) processing and restoring means beginning from the pixel data on aline of said original still image parallel to said reference line andfurthest from said reference line for processing the pixel data on aline of said original still image line by line and for restoring theprocessed pixel data to addresses of said video memory means forming aline of said processed still image.

These and other objects, features and advantages of the presentinvention will be apparent in the following detailed description ofpreferred embodiments when read in conjunction with the accompanyingdrawings, in which like reference numerals are used to identify the sameor similar parts in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are schematic diagrams useful for explaining an operationof the prior art;

FIG. 2 is a block diagram of an embodiment of the present invention;

FIG. 3 is a flow chart to which reference will be made in explaining anoperation of a first embodiment of the present invention;

FIG. 4 is a schematic diagram useful for explaining the operation thefirst embodiment of the present invention;

FIG. 5 is a flow chart to which reference will be made in explaining anoperation of a second embodiment of the present invention;

FIG. 6 is a schematic diagram useful for explaining the operation of thesecond embodiment of the present invention;

FIG. 7 is a flow chart to which reference will be made in explaining anoperation of a third embodiment of the present invention;

FIG. 8 is a schematic diagram useful for explaining the same;

FIGS. 9, 10 and 11 are schematic diagrams useful for explaining anoperation of a spline interpolation, respectively;

FIG. 12 is a flow chart to which reference will be made in explainingthe operation of the spline interpolation;

FIG. 13 is a flow chart to which reference will be made in explainingthe memory control operation for the spline interpolation;

FIGS. 14 and 15 are schematic diagrams to which reference will be madein explaining the operation for the spline interpolation, respectively;

FIGS. 16 and 17 are flow charts to which reference will be made inexplaining the operation for the spline interpolation, respectively; and

FIG. 18 is a flow chart to which reference will be made in explainingthe memory control operation for the spline interpolation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will now be described with reference to thedrawings.

Referring to the drawings in detail and initially to FIG. 2, anembodiment of the present invention which is applied to still pictureterminal apparatus will be described. In FIG. 2, it will be seen that acomputer (microcomputer) 1 is comprised of a central processing unit(CPU) 2, a read-only memory (ROM) 3 and a random access memory (RAM) 4.The ROM 3 and the RAM 4 are connected to a bus line 5 of the CPU 2. Thebus line 5 might be formed of a data bus, an address bus, a control busor the like. The computer 1 controls respective portions of a stillpicture communication terminal apparatus.

A transmission line 13 might be either wireless communication type orwire-communication type. If the transmission line 13 is a wiretransmission line, then there are available an integrated servicesdigital network (ISDN), a high speed digital network line, analogtelephone network line, digital data exchange network (DDX), specialnetwork line or the line. The DDX might be either DDXC or DDXP.

A communication processing circuit and interface 12 is connected betweenthe transmission line 13 and the bus line 5, and whose protocol andtransmission rate correspond to those of a still picture signal which istransmitted through the transmission line 13. The communicationprocessing circuit carries out encoding, modulation and so on fortransmitting data and also carries out decoding, demodulation and so onfor receiving data.

A frame memory 6 might be a video RAM, and whose digital video signalinput and output terminal and control signal input terminal areconnected to the bus line 5. The digital video signal input terminal ofthe frame memory 6 is connected to an output terminal of ananalog-to-digital (A/D) converter 10, and the digital video signaloutput terminal thereof is connected to an input terminal of adigital-to-analog (D/A) converter 7. Another control signal inputterminal of the frame memory 6 is connected to an output terminal of adisplay timing control circuit 11. The write and read of the framememory 6 are controlled by the computer 1 and the display timing controlcircuit 11. The frame memory 6 includes horizontal and vertical addresscounters, a memory controller and the like, though not shown.

An input terminal 9 is supplied with an analog video signal. The videosignal (video signal from a video camera, a video tape recorder or thelike) from the input terminal 9 is supplied to the A/D converter 10, inwhich it is converted to a digital video signal. This digital videosignal therefrom is supplied to and written in the frame memory 6.

The digital video signal read out from the frame memory 6 is convertedto an analog video signal by the D/A converter 7. The analog videosignal thus converted is supplied to a monitor receiver 8 having acathode ray tube (CRT) and is then displayed on the cathode ray tube ofthe monitor receiver 8.

The analog video signal supplied to the input terminal 9 is converted tothe digital video signal by the A/D converter 10, and is then stored inthe frame memory 6 as the digital still picture signal (whose stillpicture is a natural picture) as described above. This still picturesignal (original still picture signal) is read out from the frame memory6 under the control of the microcomputer 1, then processed (magnified,reduced or moved with the same size), and the processed still picturesignal is written and stored in the frame memory 6 at its desiredlocation instead of the original still picture signal as will bedescribed later. The digital still picture signal stored in the framememory 6 is read out, and is then supplied, under the control of themicrocomputer 1, to the communication processing circuit and interface12, in which it is processed for transmission and transmitted throughthe transmission line 13 to other still picture communication terminalapparatus.

A small storage capacity buffer memory 14 is provided, and whose digitalvideo signal input and output terminal and control signal input terminalare connected to the bus line 5. The write and read of the buffer memory14 are controlled by the microcomputer 1. This buffer memory 14 includeshorizontal and vertical address counters, a memory controller and thelike though not shown. Further, there is provided a digital signalprocessing circuit 15 whose input and output terminal is connected tothe bus line 5, and which is controlled by the microcomputer 1. Ahigh-speed access RAM 16 is provided in the digital signal processingcircuit 15, and the access speed thereof is selected to be very high ascompared with that of the video RAM 6.

FIG. 3 is a flow chart to which reference will be made in explaining howto magnify the still picture signal stored in the frame memory 6 underthe control of the microcomputer 1 as shown in FIG. 4. Prior to theexplanation on the magnifying processing, the original still picturesignal (original still picture) and the magnifying-processed stillpicture signal (magnifying-processed still picture) will be explainedwith reference to FIG. 4.

As shown in FIG. 4, a memory plane corresponding to the picture screenof the frame memory 6 is set, and an xy orthogonal coordinate system isset on the memory plane. Initially, let us assume that the originalstill picture of the original still picture signal (whose still pictureis a natural picture) stored in the frame memory 6 has a configurationof, for example, a rectangular area A₁ B₁ C₁ D₁ and that each side ofthe rectangular area A₁ B₁ C₁ D₁ is parallel to the x axis or y axis.Also, (X11, Y11), (X12, Y11), (X12, Y13) and (X11, Y13) assumecoordinates of the respective points A₁, B₁, C₁ and D₁ thereof. In thiscase, let it be assumed that pixel data of respective pixels forming theoriginal still picture having the rectangular configuration are stored,i.e. are repeated at α addresses in the x direction and at β addressesin the y direction, i.e. they are stored in α·β addresses in total sothat the magnification factor is α·β.

Further, let us assume that the magnified still picture of themagnifying-processed still picture signal of the original still picturesignal is such that the original still picture is moved parallel to adesired location on the memory plane corresponding to the picturescreen. Also, let it be assumed that the magnified still picture has arectangular area A₂ B₂ C₂ D₂, each side of the rectangular area A₂ B₂ C₂D₂ is parallel to the x axis or the y axis and that (X21, Y21), (X22,Y21), (x22, Y23) and (X21, Y23) represent coordinates of the respectivepoints A₂, B₂, C₂ and D₂, respectively. In FIG. 4, M (Xm, Ym) representsa point of intersection of lines, each of which connects correspondingpoints of the rectangular areas A₁ B₁ C₁ D₁ and A₂ B₂ C₂ D₂. A line y=Ympassing through the point M (Xm, Ym), is parallel to the x axis, whichis a reference line in this case.

In the case of FIG. 4, the whole area of the original still pictureoverlaps the magnified still picture, and even if the reference line isparallel to either the x axis or y axis, the original still picture andthe magnified still picture are divided in two by the reference line.

Let us now explain a relationship between a desired point P1 (x₁, y₁)located within the original still picture and a point P2 (x₂, y₂)located within the magnified still picture. A line connecting thesepoints P1 and P2 passes the point M of intersection. Values x₂ and y₂are functions of values x₁ and y₁ so that they are expressed as follows:

    x.sub.2 =Fx (x.sub.1)                                      (1)

    y.sub.2 =Fy (y.sub.1)                                      (2)

Since all lines connecting the points A₂, A₁ ; B₂, B₁ ; C₂, C₁ ; and D₂,D₁ pass through the intersection point M, the function equations (1) and(2) can be solved and the x and y coordinates Xm and Ym can be obtained.

An embodiment of the present invention will be described on the basis ofthe example shown in FIG. 4 with reference to the flow chart formingFIG. 3.

As shown in FIG. 3, following the Start of the operation, an equality ofy=Y11 is set by substituting means at step ST-1. y=Y11 represents a linewhich includes an upper side of the rectangular area A₁ B₁ C₁ D₁ of theoriginal still picture. The routine proceeds from step ST-1 to stepST-2.

In step ST-2, under the control of read and write control means, α pixeldata of point P1 (x₁, y₁) (corresponding addresses of the memory 6) fromcoordinates X11 to X12 on the line y=Y11 are moved to point P2 (F_(x)(X₁), F_(y) (y₁)) (corresponding addresses of the memory 6). The pointP2, in this case, is located on the upper side of the rectangular areaA₂ B₂ C₂ D₂. Then, the routine proceeds from step ST-2 to step ST-3.

In step ST-3, an equality of y=Y11-ΔY is set by the substituting means,and the routine proceeds from step ST-3 to the next decision step ST-4.

In step ST-4, it is determined by judging means whether y≧Ym isestablished or not. If it is determined that y≧Ym is established asrepresented by a YES at step ST-4, the routine returns to step ST-2. Ifon the other hand it is determined that y≧Ym is not established asrepresented by a NO at step ST-4, or if y<Ym is established, the routineproceeds to step ST-5.

Steps ST-1 to ST-4 mean that in the range of y≧Ym within the originalstill picture having the configuration of the rectangular area A₁ B₁ C₁D₁ α pixel data of each point P1 (x₁, y₁) on each line are moved to thecorresponding point P2 [Fx (x₁), Fy (y₁)] (corresponding addresses ofthe memory 6) on the line parallel to the reference line y=Ym of themagnified still picture by decrementing y from Y=Y11 by ΔY(corresponding to one address of the memory 6).

In step ST-5, y=Y13 is set by the substituting means, and the equalityof y=Y13 represents a line which includes the lower side of therectangular area A₁ B₁ C₁ D₁ of the original still picture. The routineproceeds from step ST-5 to ST-6.

In step ST-6, under the control of the read and write control means, αpixel data at the point P1 (x₁, y₁) (corresponding addresses of thememory 6) extending from X11 to X12 on the line y=Y13 are moved to thecorresponding points P2 [Fx (x₁), Fy (y₁)] (corresponding addresses ofthe memory 6) of the magnified processed still picture. In this case,the point P2 is located on the lower side of the rectangular area A₂ B₂C₂ D₂. The routine proceeds from step ST-6 to step ST-7.

In step ST-7, an equality of y=Y13+ΔY is set by the substituting means,and the routine proceeds from step ST-7 to the next decision step ST-8.

In step ST-8, it is determined by the judging means whether aninequality of y<Ym is satisfied or not. If it is determined that y<Ym issatisfied as represented by a YES at step ST-8, the routine returns tostep ST-6. If on the other hand it is determined that y<Ym is notsatisfied as represented by a NO at step ST-8, i.e. y≧Ym is satisfied,the routine is ended.

In FIG. 3, the steps ST-5 to ST-8 mean that in the range of y<Ym withinthe original still picture having the the rectangular area A₁ B₁ C₁ D₁,by incrementing y from Y=Y13 by ΔY [corresponding to one address of thememory 6], α pixel data of each point P1 (x₁, y₁) on each line are movedto the corresponding point P2 [Fx (x₁), Fy (y₁)] [correspondingaddresses of the memory 6] on the line parallel to the reference liney=Ym of the magnified still picture.

In the flow chart of FIG. 3, the system of step ST-1 to step ST-4 andthe system of step ST-5 to step ST-8 can be replaced with each other orthe two systems can be executed at the same time. In short, it is to benoted that the storing location of the pixel data of the original stillpicture signal stored in the memory is shifted at every line in such amanner that the pixels on the line parallel to the reference line of theoriginal still picture are sequentially moved from the furthest from thereference line to the nearest or from the furthest from thecorresponding reference line of the processed still picture to thenearest on a line parallel to the reference line.

While the process for magnifying or enlarging the original still pictureis explained in the above-mentioned embodiment, the reducing process forreducing an original still picture is carried out as follows. In thiscase, the still picture having a rectangular area A₂ B₂ C₂ D₂ is used asthe original still picture, while the still picture having a rectangulararea A₁ B₁ C₁ D₁ is employed as a still picture to be reduced in size.Then, the storing location of the pixel data of the original stillpicture signal stored in the memory is moved at every line in such amanner that the pixels on the line parallel to the reference line of theoriginal still picture are sequentially moved from the furthest from thereference line to the nearest or from the furthest line from thecorresponding reference line of the processed still picture to thenearest on the line parallel to the reference line.

In the case of FIG. 4, the whole of the original still picture overlapson the magnified still picture so that, even when the reference line isparallel either to the x axis or to the y axis, the original stillpicture and the magnified still picture are divided by two by thereference line. Thus, when the reference line parallel to the y axis isemployed instead of the reference line parallel to the x axis, theoperation is the same as explained above.

If the magnified still picture partly overlaps the original stillpicture as shown in FIG. 6, pixels on respective points of the originalstill picture are moved on respective points of the magnified stillpicture in different manners with respect to the reference line y=Ymparallel to the x axis passing through the intersection point M (Xm, Ym)of lines connecting corresponding points of the original still pictureand the magnified still picture and with respect to the reference linex=Xm parallel to the y axis. In other words, if the line y=Ym parallelto the x axis is employed as the reference line, the original stillpicture and the magnified still picture are divided by two by thisreference line so that the same operations as those in FIG. 3 will becarried out.

The operation in which the line x=Xm passing through the point M andparallel to the y axis is employed as the reference line will beexplained with reference to a flow chart forming FIG. 5.

As shown in FIG. 5, following the Start of the operation, an equality ofx=X11 is set by substituting means at step ST-11. The line x=X11includes the left side of the rectangular area A₁ B₁ C₁ D₁ of theoriginal still picture. The routine proceeds from step ST-11 to stepST-12.

In step ST-12, α pixel data at the point P1 (x₁, y₁) [correspondingaddresses of the memory 6] from Y11 to Y13 on the line x=X11 are movedto the point P2 [Fx (x₁), Fy (y₁)] [corresponding addresses of thememory 6] by the read and write control means. The routine proceeds fromstep ST-12 to step ST-13.

In step ST-13, an equality of x=X11+ΔX is set by the substituting means,and then the routine proceeds from step ST-13 to step ST-14. In stepST-14, it is determined by judging means whether an inequality of x≧X12is satisfied or not. If it is determined that the equality of x≧X12 issatisfied as represented by a YES at step ST-14, the routine returns tostep ST-12. If on the other hand the equality of x≧X12 is not satisfiedas represented by a NO at step ST-14, the routine is ended.

According to the steps ST-11 to ST-14, in the range of x≧X12 within theoriginal still picture having the rectangular area A₁ B₁ C₁ D₁, α pixeldata of the respective points P1 (x₁, y₁) on the lines are moved to thecorresponding points P2 [Fx (x₁), Fy (y₁)] [the corresponding addressesof the memory 6] on the line parallel to the reference line y=Ym of themagnified still picture by increasing x from x=X11 by ΔX [correspondingto one address of the memory 6].

In this example, the original still picture is magnified. When theoriginal still picture is reduced, the still picture having therectangular area A₂ B₂ C₂ D₂ is employed as the original still picture,while the still picture having the rectangular area A₁ B₁ C₁ D₁ isemployed as a still picture to be reduced. Then, the storing location ofthe pixel data of the original still picture signal stored in the memoryis moved at every line in such a manner that pixel data on the lineparallel to the reference line of the original still picture aresequentially moved to the line parallel to the reference line from thefurthest position of the reference line to the nearest position, or fromthe furthest line of the corresponding reference line of the processedstill picture to the nearest line. In this case, the processed stillpicture is the same as the original still picture in size, or it mightbe a congruent still picture.

In the above-noted explanation, the respective points of the originalstill picture and the respective corresponding points of the processedstill picture are not always the practical address points of the memory.Therefore, in practice, data of imaginary points existing among therespective points of the original still picture must be calculated bythe interpolation. Then, the calculated data must be mappped on theaddress positions of the respective points of the processed stillpicture. Then, in order to interpolate the data at the imaginary points,in general, address data at a plurality of points in the up and downdirection and the left and right direction around the imaginary pointare necessary. Thus, when the calculated data are sequentially mappedfrom the upper direction in the embodiment of FIG. 4, the data of theprocessed still picture which are converted to a region where the datanecessary for the interpolation exist are written as the mappingapproaches the reference line, y=Ym. As a result, the interpolation datais erased and there is then presented a possibility that theinterpolation will not be made.

The following embodiment of the invention is made in order to solve theabove-mentioned problem, and will be explained with reference to FIGS. 7and 8.

As shown in FIG. 8, similarly to FIG. 6, the original still picture andthe magnified still picture partly overlap with each other, and thereference line y=Ym passes through the overlapping area of the originalstill picture and the magnified still picture. Also, the reference liney=Ym divides these original still picture and magnified still picture bytwo.

A band-shaped area having a rectangular area E₁ F₁ G₁ H₁, each side ofwhich is parallel to each side of the rectangular area A₁ B₁ C₁ D₁ isprovided at both sides of the reference line y=Ym of the original stillpicture. In this event, w₁ /2 assumes each of the distances of the sidesE₁ F₁ ; and G₁ H₁ of the band-shaped area from the reference line y=Ym.Further, (X15, Y15), (X16, Y15), (X16, Y17) and (X15, Y17) assumecoordinates of the respective points E₁, F₁, G₁ and H₁.

Furthermore, a band-shaped area having a rectangular area E₂ F₂ G₂ H₂,each side of which corresponds to each side of the rectangular area A₂B₂ C₂ D₂ is provided at both sides of the reference line y=Ym of theprocessed still picture. W₂ /2 assumes each of the distances of thesides E₂ F₂ ; and G₂ H₂ of the band-shaped area from the reference line,y=Ym. Also, (X25, Y25), (X26, Y25), (X26, Y27) and (X25, Y27) assume thecoordinates of the respective points E₂, F₂, G₂ and H₂, respectively.

With above-noted arrangements, similarly to FIG. 4, the functions, x₂=Fx (x₁) and y₂ =Fy (y₁) can be calculated, and the coordinate (Xm, Ym)of the point M can also be calculated.

In association with the example shown in FIG. 8, let us explain a secondembodiment of the present invention with reference to a flow chartforming FIG. 7.

Referring to FIG. 7, following the Start of the operation, the wholepixel data of the point P₁ (x₁, y₁) of the rectangular area E₁ G₁ F₁ H₁of the original still picture having the rectangular area A₁ B₁ C₁ D₁and stored in the main memory 6 are transferred to the buffer memory 14by the write and read control means (in step ST-21). The routineproceeds from step ST-21 to step ST-22.

In step ST-22, an equality of y=Y11 is set by the substituting means.y=Y11 means a line which includes the upper side of the rectangular areaA₁ B₁ C₁ D₁ of the original still picture. Then, the routine proceedsfrom step ST-22 to step ST-23.

In step ST-23, α pixel data of the point P₁ (x₁, y₁) [correspondingaddresses of the main memory 6] from X11 to X12 on the line y=Y11 aremoved to point P₂ [Fx (x₁), Fy (y₁)] [corresponding addresses of themain memory 6] by the write and read control means. In that event, thepoint P₂ is located on the upper side of the rectangular area A₂ B₂ C₂D₂. The routine proceeds from step ST-23 to step ST-24.

In step ST-24, an equality of y=Y11-ΔY is set by the substituting means.The routine proceeds from step ST-24 to the next decision step ST-25.

In decision step ST-25, it is determined by judging means whether or notan inequality of y>Y15 is satisfied. If it is determined that y>Y15 issatisfied as represented by a YES at step ST-25, then the routinereturns to step ST-23. If on the other hand it is determined that y>Y15is not satisfied, i.e. y<Y15 is satisfied as represented by a NO at stepST-25, the routine proceeds to step ST-26.

According to step ST-22 to step ST-25, α pixel data of the point P₁ (x₁,y₁) on the respective lines are moved to the corresponding point P₂ [Fx(x₁), Fy (y₁)] [corresponding addresses of the main memory 6] on theline parallel to the reference line y=Ym of the magnified still pictureby decrementing y from y=Y11 by ΔY [corresponding to one address of themain memory 6] in a range of y>Y15 within the original still picturehaving the rectangular area A₁ B₁ C₁ D₁.

In step ST-26, an equality of y=Y13 is set by the substituting means.y=Y13 means a line which includes the lower side of the rectangular areaA₁ B₁ C₁ D₁ of the original still picture. Then, the routine proceedsfrom step ST-26 to step ST-27.

In step ST-27, α pixel data of the point P₁ (x₁, y₁) [correspondingaddress of the main memory 6] from X11 to X12 on the line y=Y13 aremoved to the corresponding point P₂ [Fx (x₁), Fy (y₁)] [correspondingaddress of the main memory 6] of the magnified still picture by thewrite and read control means. In this case, the point P₂ is located onthe lower side of the rectangular area A₂ B₂ C₂ D₂. The routine proceedsfrom step ST-27 to step ST-28.

In step ST-28, an equality of y=Y13+ΔY is set by the substituting means.Then, the routine proceeds from step ST-28 to the next decision stepST-29.

It is determined at decision step ST-29 by judging means whether or notthe inequality of y<Y17 is satisfied. If it is determined that theinequality of y<Y17 is satisfied as represented by a YES at step ST-29,the routine returns to step ST-27. If it is determined that y<Y17 is notsatisfied, or if y≧Y17 is satisfied as represented by a NO at stepST-29, the routine proceeds to step ST-30.

According to step ST-26 to step ST-29, α pixel data of the point P₁ (x₁,y₁) on each line are moved to the point P₂ [Fx (x₁), Fy (y₁)][corresponding address of the memory 6] on the line parallel to thereference line y=Y of the magnified still picture by increasing y fromy=Y13 by ΔY each in a range of y<Y17 within the original still picturehaving the rectangular area A₁ B₁ C₁ D₁.

In step ST-30, the pixel data of the processed still picture signal ofthe original still picture signal stored in the buffer memory 14 ismoved to the point P₂ [Fx (x₁), Fy (y₁)] in the band-shaped area of therectangular area E₂ F₂ G₂ H₂ within the processed still picturecorresponding to the band-shaped area of the rectangular area E₁ F₁ G₁H₁ of the original still picture signal of the main memory 6 by thewrite and read control means.

In this case, if of the original still picture having the rectangulararea A₁ B₁ C₁ D₁ stored in the main memory 6 all pixel signals withinthe rectangular area E₁ F₁ G₁ H₁ are magnified and transferred to thebuffer memory 14 by the write and read control means, in step ST-30, themagnification-processed pixel signals are directly transferred to theband-shaped area of the rectangular area E₂ F₂ G₂ H₂ of the main memory6. Alternatively, if in step ST-21 within the original still picturehaving the rectangular area A₁ B₁ C₁ D₁ stored in the main memory 6, allpixel signals within the rectangular area E₁ F₁ G₁ H₁ are directlytransferred to the buffer memory 14 by the write and read control means,in step ST-30, the original still picture signal ismagnification-processed and transferred to the band-shaped area of therectangular area E₂ F₂ G₂ H₂ of the main memory 6.

In FIG. 7, the system of step ST-22 to step ST-25 and the system of stepST-26 to step ST-29 may be replaced with each other and they may beexecuted simultaneously. In short, the storing location of the pixeldata of the original still picture signal stored in the main memory 6 ismoved at every line in such a manner that the pixel data on the lineparallel to the reference line of the original still picture issequentially transferred on the line parallel to the reference line fromthe furthest to the nearest or from the reference line corresponding tothe processed still picture from the furtheset position to the nearestposition.

If a buffer memory [whose storage capacity is very small as comparedwith that of the main memory 6] is used in addition to the main memory 6and the above-noted steps ST-21 and ST-30 are executed, when instead ofthe original still picture signal stored in the main memory 6 theprocessed still picture signal is re-stored in the main memory 6, it ispossible to avoid such a possibility that the interpolation forinterpolating the deteriorated pixel signals near the reference line andstored in the main memory becomes impossible.

According to this embodiment, the original still picture is magnified asdescribed above. When the original still picture is reduced, the stillpicture having the rectangular area A₂ B₂ C₂ D₂ is employed as theoriginal still picture and the still picture having the rectangular areaA₁ B₁ C₁ D₁ is employed as a still picture to be reduced. Under thiscondition, the above-noted operations are executed.

The interpolating method, which is applicable to the magnifying andreducing processings according to the above-noted embodiments, will beexplained below.

When in FIGS. 4, 6 and 8 the length of each side of the rectangular areaA₂ B₂ C₂ D₂ of the processed still picture is selected to be an integralmultiple, for example, twice that of each corresponding side of therectangular area A₁ B₁ C₁ D₁ of the original still picture, pixel dataof the rectangular area A₂ B₂ C₂ D₂ may be provided only byinterpolating the intermediate values of pixel data of the rectangulararea A₁ B₁ C₁ D₁.

Conversely, when the length of each side of the rectangular area A₂ B₂C₂ D₂ is selected to be 1/integral multiple, for example, 1/2 of that ofeach corresponding side of the rectangular area A₁ B₁ C₁ D₁, the pixeldata of the rectangular area A₂ B₂ C₂ D₂ may be provided by cyclicallyremoving pixel data of the rectangular area A₁ B₁ C₁ D₁. However, arelationship between the original still picture and the processed stillpicture is not always limited to those mentioned above. It is frequentlyobserved that they are in a relationship of non-integral multiple. Inthis case, if data at imaginary position located at the intermediate ofthe address position of pixel data of the original still picture iscalculated by the interpolation and the pixel data of the resultantimaginary position is transferred to the real address position of theprocessed still picture, it becomes possible to carry out the magnifyingand reducing processes.

As the above-noted interpolating method, a spline interpolation will bedescribed by way of example. The spline interpolation of one-dimensionwill be explained with reference to FIGS. 9 and 10. The most specificfeature of the spline interpolation lies in the following points: Acurve provided by the interpolation passes through all of samplingpoints; it has no discontinuous points; it is short in calculation time;it is increased in information band by the complete convolution; and itbecomes a cubic curve.

The spline function is expressed by the sum of interval functionsexpressed by a cubic function which differs at every interval betweentwo sampling points. More specifically, the spline function is afunction equal to a cubic function of f₀ (x)=a₀ x³ +b₀ x² +c₀ x+d₀ whichis uniquely determined at four points, (x₋₁, f₋₁), (x₀, f₀), (x₁, f₁)and (x₂, y₂) in the interval of [x|x₀₋ ≦x<x₁ ] as shown in FIG. 9. Whenthe above-noted cubic function is generalized, it is expressed by thefollowing equation (refer to FIG. 10).

    f(x)=a.sub.n x.sup.3 +b.sub.n x.sup.2 +c.sub.n x.sup.2 +d.sub.n (x.sub.n ≦x<x.sub.n+1)

where (a_(n), b_(n), c_(n), d_(n)) is given by the following equation.##EQU1## where x is the normalized value for x which is x_(n)≦x<x_(n+1).

The idea of the above-mentioned spline interpolation is enlarged to thetwo-dimension, and this will be described with reference to FIG. 11. Letus consider how to obtain pixel data at an imaginary point Q. When thepixel data at the imaginary point Q is obtained, points g₀, g₁, g₂ andg₃ are obtained first and then the pixel data at the imaginary point Qis obtained on the lines connecting the above-mentioned points g₀, g₁,g₂ and g₃ as follows. ##EQU2##

Accordingly, pixel data Q at the point Q is expressed as ##EQU3##

Thus, the pixel data Q is obtained by the following equation. ##EQU4##

(A) is expressed by the following equation, and (A^(t)) is thetransposed matrix of (A) ##EQU5##

If =(1, y, y², y³), ##EQU6## then, the pixel data Q is expressed by aninner product of five matrices as follows.

    Q= · .sup. · · ·

The calculation processing for obtaining the pixel data P₂ (x₂, y₂)=(y₁)· .sup. · (x₁, y₁)· · (x₁) at the point P₂ corresponding to pixeldata P₁ (x₁, y₁) at the point P₁ in FIG. 4 will be explained withreference to a flow chart forming FIG. 12.

Referring to FIG. 12, following the Start of operation, y=start-Y(initial value) is set at step ST-31, and then x=start-X (initial value)is set at step ST-32. Then, = · (x) is calculated in step ST-33 whererepresents temporary matrix of (1×n). = (x, y)· is calculated in stepST-34, and then = .sup. · is calculated at step ST-35. P(x, y)= (y)· iscalculated at step ST-36, and x=x+1 is set in step ST-37. Then, theroutine proceeds to the next decision step ST-38, whereat it isdetermined whether x is equal to end - X (final value) or not. If a NOis output at step ST-38, the routine returns to step ST-32. If on theother hand a YES is output at step ST-38, the routine proceeds to stepST-39. y=y+1 is set in step ST-39. Then, the routine proceeds to thenext decision step ST-40, whereat it is determined whether y is equal toend -Y (final value) or not. If a NO is output in step ST-40, theroutine returns to step ST-32, while if a YES is output at step ST-40,the routine is ended.

The above-noted calculation processing in the example shown in FIG. 12has a very long processing time.

An example in which interpolation calculations for a plurality ofimaginary points are carried out successively will be explained withreference to a flow chart forming FIG. 13. As, for example, shown inFIG. 14, when magnified pixel data q₀, q₁, q₂, . . . q₁₅, . . . .forming magnified still picture data are obtained from original pixeldata P₀, P₁, P₂, . . . , P₁₄ forming original still picture data, themagnified pixel data q₁ is obtained by the calculation using, forexample, 3×3 original pixel data P₀, P₁, P₂, P₅, P₆, P₇, P₁₀, P₁₁ andP₁₂. Further, the magnified data q₂ is obtained by the calculation using3×3 original pixel data P₀, P₁, P₂, P₅, P₆, P₇, P₁₀, P₁₁ and P₁₂.

In this way, the original pixel data necessary for the above-notedcalculation are repeatedly read out from the video memory.

This will be described with reference to the flow chart of FIG. 13.

Referring to FIG. 13, following the Start of operation, 3×3 originalpixel data from the video memory (video RAM) 6 in which the originalstill picture data are stored as shown in FIG. 2 are transferred to thework RAM 16 in the digital signal processing circuit 15 at step ST-41.Then, the calculation is carried out by using 3×3 pixel data stored inthe work RAM 16 to provide one magnified pixel data at step ST-42. Then,the routine proceeds to the next decision step ST-43, whereat it isdetermined whether or not the predetermined calculation is ended. If aNO is output at step ST-43, the routine returns to step ST-41. If a YESis output at step ST-43, the routine is ended. The magnified pixel dataq₀, q₁, q₂, . . . thus calculated are re-stored in the original videoRAM as Q₀, Q₁, Q₂, . . . instead of the original pixel data as shown inFIG. 15.

As described above, to repeatedly read the original pixel data from thevideo RAM needs plenty of time, which unavoidably provides an increasedprocessing time.

Next, a method which eliminates the above defect will be described.

In FIG. 14, since P (x, y) represents all points which exist in atwo-dimensional space formed of 0≦x <m and 0≦y<n, all x forming of 0˜m-1 and all y forming of 0˜n -1 are pre-processed so as to form vectorarrangements of (x)= (x) and (y) .sup. . Accordingly, with theemployment of these vector arrangements and , P (x, y) is calculated as

    P (x, y)= (y)· (x, y)· (x)

Thus, the number of product and sum calculations is reduced to n³ andthe processing time is about one second. Also, the ratio thereof becomes1:4000.

The above-noted pre-processing in this example will be explained withreference to a flow chart forming FIG. 16.

Referring to FIG. 16, following the Start of operation, x=start-X(initial value) is set at step ST-51. (x)= · (x) is calculated in stepST-52, and x is set as x+1 in step ST-53. The routine proceeds to thenext decision step ST-54, whereat it is determined whether or not xbecomes a final value, end - X. If a NO is output at step ST-54, theroutine returns to step ST-52. If a YES is output in step ST-54, theroutine proceeds to step ST-55.

In step ST-55, y=start-Y (initial value) is set, and (y)= (y)· .sup. iscalculated in next step ST-56. In next step ST-57, y=y+1 is set, and theroutine proceeds to the next decision step ST-58, wherein it isdetermined whether or not y is equal to end - Y. If a NO is output instep ST-58, the routine returns to step ST-56. If a YES is output atstep ST-58, the routine proceeds to the return (step ST-59).

The main processing following the pre-processing will be explained withreference to a flow chart forming FIG. 17.

Referring to FIG. 17, following the Start of operation, after thepre-processing shown in FIG. 16 is carried out in step ST-61, y=start-Y(initial value) is set in step ST-62. Then, x=start-X (initial value) isset in step ST-63, and = (x, y)· (x) is calculated at next step ST-64where represents the temporary matrix. In the following step ST-65, P(x,y)= ()· is calculated, and x=x+1 is set in next step ST-66. Then, theroutine proceeds to the next decision step ST-67, wherein it isdetermined whether or not x is equal to end - X (final value). If a NOis output at step ST-67, then the routine returns to step ST-63. If onthe other hand a YES is output at step ST-67, then the routine proceedsto step ST-68, wherein y=y+1 is set. It is determined at the nextdecision step ST-69 whether or not y is equal to end - Y (final value).If a NO is output at step ST-69, then the routine returns to step ST-63.If a YES is output in step ST-69, then the routine is ended.

How to prevent the processing time from being increased when theoriginal pixel data are repeatedly read out from the video RAM 6 will beexplained with reference to a flow chart forming FIG. 18.

Referring to FIG. 18, following the Start of operation, at step ST-713×3 original pixel data (for example, P₀, P₁, P₂, P₅, P₆, P₇, P₁₀, P₁₁,P₁₂ shown in FIG. 14) read out from the video RAM 6 in which originalstill picture data are stored are transferred to the work RAM 16 in thedigital signal processing circuit 15 (in step ST-71).

In the next step ST-72, the calculation is carried out by using 3×3original pixel data P₀, P₁, P₂, P₅, P₆, P₇, P₁₀, P₁₁, P₁₂ stored in thework RAM 16 to provide and deliver one magnified pixel data (q₁ in FIG.14). The magnified pixel data q₁ thus delivered is written in the videoRAM 6 at its predetermined address through the buffer memory 14 as shownin FIG. 15 and then stored therein.

Then, it is determined at step ST-73 whether or not the necessarycalculation is ended. If a YES is output at step ST-73, the routine isended. If a NO is output at step ST-73, the routine proceeds to the nextdecision step ST-74.

It is determined at step ST-74 whether or not the imaginary position ofthe processed pixel data moves to the adjacent position. If an answer atstep ST-74 is a YES, the imaginary position moves to the positionbetween the original pixel data P₁, P₆, P₁₁ ; and P₂, P₇, P₁₂, so thatthe routine moves to step ST-75. It is also determined at step ST-74whether or not the imaginary position moves from the position betweenP₀, P₅, P₁₀ ; and P₁, P₆, P₁₁ to the position between the original pixeldata P₀, P₅, P₁₀ ; and P₂, P₇, P₁₂. If a NO is output at step ST-74,then the routine proceeds to step ST-76. If a YES is output at stepST-74, then the routine proceeds to step ST-75.

In the example of FIG. 14, the imaginary position of the processed pixeldata is changed from q₁ to q₂ and is moved to the position between theoriginal pixel data P₀, P₅, P₁₀ ; and P₂, P₇, P₁₂ so that the routineproceeds to step ST-75.

In step ST-75, 3×n, in this example, 3×2 original pixel data P₁, P₂, P₆,P₇, P₁₁, P₁₂ are transferred to the predetermined addresses of the workRAM 16, and new 3×(3-n), in this example, 3 original pixel data P₃, P₈and P₁₃ from the video RAM 6 are transferred to the work RAM 16. Then,the routine proceeds to step ST-76.

In step ST-76, the calculation is carried out by using 3×3 originalpixel data P₁, P₂, P₃, P₆, P₇, P₈, P₁₁, P₁₂ and P₁₃ stored in the workRAM 16 to provide and deliver one data q₂ is written in the video RAM 6as its predetermined address via the buffer memory 14 as shown in FIG.15 and then stored therein. Then, the routine proceeds to the nextdecision step ST-77.

It is determined in step ST-77 whether or not the necessary calculationis ended. If a YES is output at step ST-77, the routine is ended. If aNO is output at step ST-77, then the routine returns to step ST-74.

In this manner, the magnified pixel data q₃, q₄, q₅, q₆, q₇, . . . arecalculated and outputted, and are written in the video RAM 6 at itspredetermined addresses as shown in FIG. 15.

While in the above-mentioned embodiment the magnifying processing iscarried out, the present invention is also applied to the reducingprocessing. In this case, the original pixel data should be properlyselected and removed.

Having described preferred embodiments of the invention in detail withreference to the accompanying drawings, it is to be understood that thepresent invention is not limited to those precise embodiments and thatmany changes and modifications could be effected by one skilled in theart without departing from the spirit and scope of the invention asdefined by the appended claims.

We claim as our invention:
 1. A method of processing original stillpicture data which represents an original still image and is stored in avideo memory and storing processed still picture data representing theoriginal still image after having been changed in size in apredetermined location of the video memory, the method comprising thesteps of:(a) setting an XY orthogonal coordinate system on the videomemory; (b) setting a reference line on the video memory parallel to oneof the X and Y axes of the orthogonal coordinate system and passingthrough a point of intersection of hypothetical lines, each of which isto connect corresponding pixels of the original and changed in sizestill images; (c) moving α replications of each pixel data on a line ofthe original still image parallel to the reference line and furthestfrom the reference line to addresses of the video memory forming a lineof the changed in size still image, where α is a real, positive numberother than zero; and (d) repeating the preceding step for pixel data onlines of the still image parallel to the reference line and nextfurthest from the reference line and the succeeding lines, to therebystore the processed still picture data representing the changed in sizestill image in the video memory.
 2. A method according to claim 1,wherein α is a real integer and the changed in size still image is anenlarged image of the original still image.
 3. A method according toclaim 1, wherein α is a fraction and the changed in size still image isa reduced image of the original still image.
 4. A method according toclaim 1, further comprising a step of storing pixel data close to thereference line in buffer memory means prior to the moving step.
 5. Amethod according to claim 4, wherein the pixel data close to thereference line belongs to a rectangular area of the original still imageparallel to the reference line.
 6. A method according to claim 5,wherein the step of storing comprises the step of directly storing thepixel data in the buffer memory means and further comprising the stepssucceeding to the step of repeating of processing the pixel data in therectangular area and of moving the processed pixel data to a rectangulararea of the changed in size still image in the video memory.
 7. A methodaccording to claim 5, wherein the step of storing includes the steps ofprocessing the pixel data in the rectangular area and storing theprocessed pixel data in the buffer memory means and further comprising astep succeeding to the step of repeating of moving the processed pixeldata stored in the buffer memory means to a rectangular area of thechanged in size still image of the video memory.
 8. An apparatus forprocessing an original still picture data representing an original stillimage and generating a processed still picture data representing achanged in size still image comprising:(a) video memory means forstoring the original still picture data and the processed still picturedata; (b) means for setting an XY orthogonal coordinate system on thevideo memory means; (c) means for setting a reference line parallel toone of one of the X and Y axes of the orthogonal coordinate system andpassing through a point of intersection of hypothetical lines, each ofwhich connects corresponding pixels of the original and change in sizestill images; and (d) processing and restoring means for replicating andtransferring pixel data of the original still image line by line,beginning from the pixel data on a line of the original still imageparallel to the reference line and furthest from the reference line andfor restoring the processed pixel data to addresses of the video memorymeans forming a line of the changed in size still image, and repeatingthe process for the next furthest and each succeeding line of theoriginal still image.